Flow restrictor and drilling assembly

ABSTRACT

A flow restrictor comprising a body adapted to restrict a flow of fluid through a drill rod passage, the body having a coupling for coupling said body into the drill rod passage, said body defining an upstream fluid receiving passage, a downstream fluid egress passage, and a passage of restrictive diameter between said passages to limit the flow of fluid in the drill rod passage.

FIELD

The present disclosure relates generally to drilling operations, drillrods and components thereof and drilling assemblies.

BACKGROUND

It is necessary during all drilling operations to deliver a fluid, suchas water, to the cutting face to remove debris as it forms around thedrill bit and, in some instances, to cool the drill tips. The fluid canbe delivered to the drill bit by passing the fluid through a centralpassage of the drill rod.

In mining operations, such as underground coal mines, substantialvolumes of water are used in drilling operations and consequentlysimilar volumes of waste water are generated. The waste water mayaccumulate and provide a safety hazard in the vicinity of miningoperations, such as underground mine roadways, and therefore requiresdisposal or mitigating measures to be implemented.

The above references to the background art do not constitute anadmission that the art forms a part of the common general knowledge of aperson of ordinary skill in the art. The above references are also notintended to limit the flow restrictor and drill assembly as disclosedherein.

SUMMARY OF THE DISCLOSURE

In a first aspect there is disclosed a flow restrictor comprising a bodyadapted to restrict a flow of fluid through a drill rod passage, thebody having a coupling for coupling said body into the drill rodpassage, said body defining an upstream fluid receiving passage, adownstream fluid egress passage, and a passage of restrictive diameterbetween said passages to limit the flow of fluid in the drill rodpassage. In one embodiment, said passages are concentrically alignedwith one another along a central longitudinal axis of the drill rodpassage.

In one embodiment, the passage of restrictive diameter may vary indiameter from, but is not limited to, a range of about 25% to about 50%of the diameter of the drill rod passage. In one form, the passage ofrestrictive diameter has a circular cross-section.

In one embodiment, the upstream fluid receiving passage inwardly tapersfrom an upstream end thereof to the passage of restrictive diameter. Inone form, the upstream end of said passage has a diameter greater than,though not limited to, about 60% of the diameter of the drill rodpassage.

In one form, the downstream end of the flow restrictor is adapted toreceive a rotary drive tool, such as a screw driver, to screw the flowrestrictor into the passage. In one embodiment, the downstream fluidegress passage has a polygonal cross-section. In one form, the polygonalcross-section may be hexagonal, star-shaped, square, or a rectangularslot. It will be appreciated that the flow restrictor may be driven intothe drill rod passage by engaging the downstream fluid egress passagewith the rotary drive tool having a complementary shaped head. In oneform, the downstream fluid egress passage is of similar diameter to theupstream end of the upstream fluid receiving passage.

In one embodiment, the coupling is a threading disposed on an externalsurface of the body, wherein the coupling is configured to complement athreading on an internal wall of the drill rod defining the passagetherethrough.

In a second aspect, there is disclosed a flow restrictor comprising abody adapted to restrict a flow of fluid through a drill rod passage,the body having an interior passage to enable fluid flow through thebody and an external threading arranged to engage an internal threaddisposed within the passage of the drill rod, said restrictor beingconfigured in use to be disposed inboard of an end of the drill rod soas to allow connection of a drill bit to said drill rod end with athreaded stem of said drill bit engaging said internal thread of saiddrill rod.

In one form, a downstream end of the flow restrictor is adapted toreceive rotary drive tool, such as a screw driver, to screw the flowrestrictor into the passage. In one form, the downstream end has apolygonal cross-section. In one form, the polygonal cross-section may behexagonal, star-shaped, square, or a rectangular slot.

In a third aspect of the disclosure, there is provided a drill rodassembly comprising a drill rod having a drill rod passage for passing aflow of fluid therethrough, and a flow restrictor disposed within thedrill rod passage and comprising a body adapted to restrict a flow offluid through the drill rod passage.

In one form, the flow restrictor body has a coupling for coupling saidbody to the drill rod passage. In one form, the body has an externalthreading arranged to engage an internal thread disposed within thepassage of the drill rod.

In one form, the restrictor is disposed inboard of an end of the drillrod and the drill rod includes a coupling at said drill rod end toengage with a drill bit to connect the drill bit to said drill rod. Inone form, the drill rod coupling is part of an internal thread of saiddrill rod to which the flow restrictor is attached.

In one form, said flow restrictor body defines an upstream fluidreceiving passage, a downstream fluid egress passage, and a passage ofrestrictive diameter between said passages to limit the flow of fluid inthe drill rod passage or port means of the drill bit.

In a further aspect, the disclosure provides a drill bit arrangementhaving a shank adapted to be closely engaged by a drill rod, said drillbit having at least one drill bit passage therein capable ofcommunicating with a drill rod passage of said drill rod to receive aflow of fluid therefrom, said drill bit further comprising a flowrestrictor comprising a body adapted to restrict a flow of fluid fromsaid drill rod passage in, or entering, the drill bit passage.

In one form, the drill bit and flow restrictor are integrally formed, orconnected to, together. In another form, the drill bit and flowrestrictor are separately formed and are arranged to individually beconnected to the drill rod.

In one form, the flow restrictor is arranged to be disposed adjacent tothe drill bit so as to regulate the flow of fluid entering the drill bitpassage. In another form, the flow restrictor is inserted in the drillbit passage. In either form, the flow restrictor may be arranged befitted as a separate operation so as to allow an operator to modify theflow requirements of a drill assembly either on site or aftermanufacture o the drill bit or drill rod.

In one form, the flow restrictor is as otherwise described above inaccordance with the earlier aspects of the disclosure

Embodiments disclosed allow a reduction in the volume and flow of waterdelivered to the drill bit, whilst enable effective performance ofdrilling operations, and consequently allows a reduction in the flow ofwater generated during drilling operations. A further advantage ofembodiments of the disclosure is that a flow restrictor can beretrofitted to exiting drilling assemblies without requiring anymodification to the drill rod and/or drill bits.

BRIEF DESCRIPTION OF THE FIGURES

Notwithstanding any other forms which may fall within the scope of thedisclosure as set forth in the Summary, specific embodiments will now bedescribed, by way of example only, with reference to the accompanyingdrawings in which:

FIG. 1 is a perspective view of a flow restrictor in accordance with onespecific embodiment;

FIG. 2 is a plan view of the flow restrictor shown in FIG. 1;

FIG. 3 is a longitudinal cross-sectional view of the flow restrictor,taken along line A-A of FIG. 2;

FIG. 4 is an upper plan view of a drilling rod assembly in accordancewith one specific embodiment;

FIG. 5 is a longitudinal cross-sectional view of the drilling rodassembly, along line B-B of FIG. 4;

FIG. 6 is an exploded view of the drilling rod assembly shown in FIGS. 4and 5;

FIG. 7 is a longitudinal section of a drilling assembly including theflow restrictor of FIG. 1; and

FIG. 8 is variation of the drilling assembly of FIG. 8.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

The description broadly relates to a flow restrictor adapted to restricta flow of fluid, such as water, through a drill rod passage, a drillbit, and a drilling rod assembly.

Referring to FIGS. 1 to 3 there is shown one embodiment of a flowrestrictor 10. The flow restrictor 10 comprises a body 12 in the form ofa cylindrical section 14 that is configured to be received in asubstantially water-tight fit in a drill rod passage 16 of a drill rod34 as shown in FIGS. 4 to 6. The cylindrical section 14 has an upstreamside 18 and a downstream side 20 (oriented on the general direction offlow of fluid through the drill rod 34. The flow restrictor includes acoupling arrangement to connect the restrictor to the drill rod, whichin the illustrated form is formed as a threading on the surface 22 ofthe cylindrical section 14 to facilitate engagement of the flowrestrictor 10 with a complementary threaded internal passage 24 of thedrill rod passage 16.

In the form as illustrated, the body 12 defines a series ofconcentrically aligned passages therethrough in the form of an upstreamfluid receiving passage 26, a downstream fluid egress passage 28, and apassage 30 of restrictive diameter between said passages 26, 28. Thepassages 26, 28, 30 are arranged, in use, to be disposed along a centrallongitudinal axis of the drill rod passage 16.

The upstream fluid receiving passage 26 directs fluid flow from thedrill rod passage 16 to the passage 30 of restrictive diameter of theflow restrictor 10. The upstream fluid receiving passage 26 inwardlytapers from an upstream end 32 located at the upstream side 18 of thecylindrical section 14 to the passage 30 of restrictive diameter. Itwill be appreciated, therefore, that the upstream end 32 has a greaterdiameter than the passage 30 of restrictive diameter. In some forms ofthe flow restrictor 10, the upstream end 32 of said passage 26 may havea diameter greater than about 60% of the diameter of the drill rodpassage 16. Generally, the diameter of the upstream end 32 of saidpassage 26 will be marginally narrower than an internal diameter of thedrill rod. The upstream fluid receiving passage 26 may extend to about50% of a total length of the flow restrictor 10.

The passage 30 of restrictive diameter is configured to restrict theflow of fluid in the drill rod passage 16 without reducing theperformance of the drill bit. The performance of the drill bit will bediminished if insufficient flow of fluid is available to pass around thedrill bit and flush drill cuttings therefrom. In some forms of the flowrestrictor 10, the passage 30 is cylindrical with a circularcross-section. The restrictive diameter may vary from about 25% to about50% of the diameter of the drill rod passage 16, although a restrictivediameter outside this range may be selected depending on the desireddrill performance characteristics and the degree of water flow reductionrequired.

The downstream fluid egress passage 28 directs fluid flow from the flowrestrictor 10, in particular from the passage 30 of restrictivediameter, to the drill rod passage 16. In In the form, shown, thedownstream fluid egress passage 28 has a constant cross-sectionaldiameter along its length which is greater than the restrictive diameterof passage 30. In one form of the flow restrictor 10, the passage 28 isof similar diameter to the upstream end of the 32 of the upstream fluidreceiving passage 26.

It is to be appreciated that the internal passage(s) in the flowrestrictor may be other than described above and illustrated. Forexample the angle of the tapered upstream fluid receiving passage 26 aswell as the passage 30 of restrictive diameter may vary due tomanufacturing procedures and different flow needs.

In the flow restrictor 10 shown in the Figures, the downstream fluidegress passage 28 has a hexagonal cross-section. It will be appreciated,however, that the downstream fluid egress passage 28 may havealternatively shaped polygonal cross-sections, such as in the form of amulti-sided star, square, or rectangular. Advantageously, acomplementary shaped head of an internal wrenching drive means may bereceived in said passage 28 to facilitate engagement of the flowrestrictor 10 in the drilling rod passage 16, as shown in FIGS. 4-6, byscrewing the body 12 of the flow restrictor 10 into the threadedinternal wall 24 of the drilling rod passage 16.

In this way, the flow restrictor 10 may be conveniently screwed into thedrilling rod passage 16 with the wrenching drive means, and may be laterremoved therefrom in the same manner.

A further feature of the flow restrictor 10 as illustrated is that itdesigned to be located in the internal thread 24 in the drill rod whichis used to couple a drill bit to the rod. In particular the body of theflow restrictor is designed to be sufficiently thin to locate in theinternal passage of drill rods whilst still allowing sufficient exposedinternal thread to receive the drill bit. In use, the internal thread istypically designed about 13 mm longer than the shank of the drill bitand it is this excess thread that in the illustrated form is used toaccommodate the flow restrictor 10. In this way the flow restrictor canbe easily retrofitted to existing drilling assemblies.

FIG. 7 illustrates the drilling assembly including the flow restrictor10, installed within the drill rod 34. A drill bit 40 having a body 42and shank 44 is installed on the drill rod 34. In the illustrated form,the shank 44 of the drill bit is threaded and matches the internalthread 24 of the drill rod, the shank length approximates the freelength 46 of the internal thread after the flow restrictor is installedsuch that the positioning of the flow restrictor 10 does not impedenormal connection of the drill bit to the drill rod.

The drill bit includes an internal passage 48 that is in fluidcommunication with the drill rod passage 16 and the flow restrictor, byreducing the diameter of the passage 16, restricts the flow into thedrill bit passage 48. As can be seen the narrowest portion of the flowrestrictor passage (the central portion 30) is narrower than thediameter of the drill bit passage so that flow restrictor reduces theflow through the drill rod 16 to a greater extent that any restrictionto flow that may occur by installation of the drill bit on the drillrod.

EXAMPLES

A non-limiting example of a method employing the flow restrictor 10 ofFIGS. 1 to 3 will now be described to illustrate how the flow restrictor10 may be applied, for example, to drilling operations in respect ofcoal mining.

Four flow restrictors 10 with respective passages 30 of varyingrestrictive diameters were trialled to determine the effectiveness ofwater flow reduction on the performance of a drill bit and theconsequent reduction of residual water in the roadway in the drillingvicinity. Visual observations were made with regard to whether there wasa positive or negative effect on the extent of flushing the hole beingdrilled.

The drill rod used in the trial had a drill rod passage diameter of 12.7mm and the drill bit had a corresponding diameter of 7 mm. The flow rateof water through the drill rod passage where a flow restrictor 10 wasnot used was 35 L/min.

The Table shows the effect of the respective passages 30 of varyingrestrictive diameters on the flow rate and flushing effect.

TABLE Diameter (mm) of Passage 30 3.1 4.7 5.6 6.3 Flow (L/min) 13 19 2827 Flushing Effect Negative Negative No discernable No discernableeffect effect

Each of the four flow restrictors 10 used in the trial decreased theflow rate of water through the drill rod passage 16 while stillproviding a flushing effect. No blockages of the drill bit wereencountered during the trial and accordingly were effective in providingflushing to the cutting face.

Based on the trials, the 5.6 and 6.3 holes were considered to exhibitless than ideal reduction in flow rates. Whilst the 3.1 hole showed themost significant reductions in flow rate (down from 35 L/min to 13L/min) there was concern that in commercial operation in some strata,the passage may become blocked. Accordingly the preferred configurationfrom the trial was the 4.7 hole which provided a reduction in flow rateof 16 L/min (from 35 L/min to 19 L/min). This configuration provided ahigh percentage reduction in flow rate whilst considered to be lesslikely to become blocked.

Numerous variations and modifications will suggest themselves to personsskilled in the relevant art, in addition to those already described,without departing from the basic inventive concepts. All such variationsand modifications are to be considered within the scope of the presentinvention, the nature of which is to be determined from the precedingdescription.

For example, it will be appreciated that the flow restrictor 10 may bereadily adapted for incorporation with a drill bit to restrict the flowof fluid entering the drill bit from the drill rod passage or may evenbe incorporated within the drill bit itself. In one form, the flowrestrictor of this variation may be retrofitted into the drill bit bybeing screwed or pressed into an internally threaded or otherwise formedcavity within the drill bit. Such an arrangement of a removable flowrestrictor 100 inserted in the drill bit 60 is shown in FIG. 8. In theillustrated form the flow restrictor 100 is screw threaded into apurpose designed internal threading 62 in the drill bit shank 64 of thedrill bit.

In the claims which follow, and in the preceding description, exceptwhere the context requires otherwise due to express language ornecessary implication, the word “comprise” and variations such as“comprises” or “comprising” are used in an inclusive sense, i.e. tospecify the presence of the stated features but not to preclude thepresence or addition of further features in various embodiments of theapparatus and method as disclosed herein.

1. A flow restrictor comprising a body adapted to restrict a flow offluid through a drill rod passage, the body having a coupling forcoupling said body into the drill rod passage, said body defining anupstream fluid receiving passage, a downstream fluid egress passage, anda passage of restrictive diameter between said upstream and downstreamfluid passages to limit the flow of fluid in the drill rod passage. 2.The flow restrictor according to claim 1, wherein said passages areconcentrically aligned with one another along a central longitudinalaxis of the drill rod passage.
 3. The flow restrictor according to claim1, wherein the passage of restrictive diameter has a diameter from about25% to about 50% of the diameter of the drill rod passage.
 4. The flowrestrictor according to claim 1, wherein the passage of restrictivediameter has a circular cross-section.
 5. The flow restrictor accordingto claim 1, wherein the upstream fluid receiving passage inwardly tapersfrom an upstream end thereof to the passage of restrictive diameter. 6.The flow restrictor according to claim 5, wherein the upstream end ofsaid passage has a diameter greater than about 60% of the drill rodpassage.
 7. The flow restrictor according to claim 1, wherein thedownstream fluid egress passage has a polygonal cross-section.
 8. Theflow restrictor according to claim 7, wherein the polygonalcross-section is hexagonal, star-shaped, square, or a rectangular slot.9. The flow restrictor according to claim 7, wherein the polygonalcross-section is adapted to receive a complementary shaped head of arotary drive
 10. The flow restrictor according to claim 5, wherein thedownstream fluid egress passage has a similar diameter to the upstreamend of the upstream fluid receiving passage.
 11. The flow restrictoraccording to claim 1, wherein the coupling is a threading disposed on anexternal surface of the body, the threading being complementary to athreading on an internal wall of the drill rod defining the passagetherethrough.
 12. A flow restrictor comprising a body adapted torestrict a flow of fluid through a drill rod passage, the body having aninterior passage to enable fluid flow through the body and an externalthreading arranged to engage an internal thread disposed within thedrill rod passage, said restrictor being configured in use to bedisposed inboard of an end of the drill rod so as to allow connection ofa drill bit to said drill rod end with a threaded stem of said drill bitengaging said internal thread of said drill rod.
 13. A drill rodassembly comprising a drill rod having a drill rod passage for passing aflow of fluid therethrough, and a flow restrictor disposed within thedrill rod passage and comprising a body adapted to be restrict a flow offluid through the drill rod passage.
 14. A drill rod assembly accordingto claim 13, wherein the flow restrictor is disposed inboard of an endof the drill rod and the drill rod includes a coupling at said drill rodend to engage with drill bit to connect the drill bit to said drill rod.15. A drill bit arrangement having a shank adapted to be closely engagedby a drill rod, said drill bit having at least one internal passagetherein capable of communicating with a drill rod passage of said drillrod to receive a flow of fluid therefrom, said drill bit furthercomprising a flow restrictor comprising a body adapted to restrict aflow of fluid from said drill rod passage in, or entering, the drill bitpassage.
 16. A drill bit arrangement according to claim 15, wherein theflow restrictor is formed separate to the drill bit and is coupled tothe drill bit.
 17. A drill bit arrangement according to claim 16,wherein the flow restrictor is disposed within the drill bit passage.18. (canceled)
 19. (canceled)